I’ve used twitter cards before thru a plugin in Wordpress, but not coding them.
I’ve created this code, and put it on the header section, but the twitter card validator displays this error: “Unable to render Card preview”

Here is the code:

<meta name="twitter:card" content="summary_large_image">
<meta name="twitter:site" content="@bpmsupreme">
<meta name="twitter:title" content="Win a DJ Set Up Worth Over $6,000">
<meta name="twitter:description" content="Delivered Just in Time for the Holidays. Win a Pioneer DJM 900 NXS2, 2x CDJs 2000NXS2, a full year BPM Supreme Membership, and a full djay PRO software license. Enter to win now!">
<meta name="twitter:image" content="https://gallery.mailchimp.com/ab34cbe175a40871ac4fda2a2/images/cdbd1ef4-a590-43cf-aeda-3236ce0dce49.jpg">

If you check the troubleshooting pinned post (that should have been referenced from the topic template when you started this new topic) you’ll find we’re unable to help without more information and details.